Respuesta :
Answer:
The 90% confidence interval for the mean production rate fro the new method is (75.9, 84.1).
Step-by-step explanation:
We have to calculate a 90% confidence interval for the mean.
The population standard deviation is not known, so we have to estimate it from the sample standard deviation and use a t-students distribution to calculate the critical value.
The sample mean is M=80.
The sample size is N=18.
When σ is not known, s divided by the square root of N is used as an estimate of σM:
[tex]s_M=\dfrac{s}{\sqrt{N}}=\dfrac{10}{\sqrt{18}}=\dfrac{10}{4.24}=2.36[/tex]
The degrees of freedom for this sample size are:
[tex]df=n-1=18-1=17[/tex]
The t-value for a 90% confidence interval and 17 degrees of freedom is t=1.74.
The margin of error (MOE) can be calculated as:
[tex]MOE=t\cdot s_M=1.74 \cdot 2.36=4.1[/tex]
Then, the lower and upper bounds of the confidence interval are:
[tex]LL=M-t \cdot s_M = 80-4.1=75.9\\\\UL=M+t \cdot s_M = 80+4.1=84.1[/tex]
The 90% confidence interval for the mean production rate fro the new method is (75.9, 84.1).
